Question

An electron placed in uniform magnetic field H(vector) that
points in xcap direction.The hamiltonian of the system
isH=-K[S(vector).H(vector)], where K›0 is a constant and S(vector)
is the electron spin operator.

A) the energy of the ground state of the hamiltonion is

1. -KSh

2. (1/2)KHh

3. -(1/2)KHh

4. 0

B) the expectation value of Sz in the ground state of
this Hamiltonion is